Unit for checking the dosing of pharmaceutical material in a capsule filling machine

ABSTRACT

A unit ( 6 ) for checking the dosing of pharmaceutical material (M) in a capsule filling machine ( 1 ) for the production of capsules (CF) of the type with a capsule lid (C) and a capsule body (F), the machine ( 1 ) comprising a fixed structure ( 15 ) fitted with a rotary drum ( 2 ) for supporting a plurality of capsules (CF) on its edge, opening each capsule (CF) by separating the capsule lid (C) from the capsule body (F), filling the capsule body (F) with a dose of material (M), then closing the capsule body (F) again with the relative capsule lid (C); the rotary drum ( 2 ) having a tank ( 5 ) containing the pharmaceutical material (M) and supporting a plurality of doser elements ( 3 ), each comprising at least one piston ( 8 ) sliding inside a hollow cylinder ( 4 ) to pick up and compress a dose (DS) of material (M) from the tank ( 5 ) and discharge it into a capsule body (F) of a capsule (CF). The unit ( 6 ) comprises sensor means ( 9 ) attached to each piston ( 8 ) for detecting a piston ( 8 ) thrust value (V; V 1 ) on the dose (DS) and transmitter means ( 10 ) connected to the sensor means ( 9 ) for transmitting the value (V; V 1 ) to a receiver element ( 11; 41 ) by the telemetric transmission of a relative signal (S; S 1 ), said receiver element ( 11; 41 ) being fixed on the machine ( 1 ) in at least one zone (P 1;  P 2 ) of the fixed structure ( 15 ). Power supply means ( 12, 14   a ) are also provided for cyclically activating the sensor means ( 9 ) and the transmitter means ( 10 ) during drum ( 2 ) rotation.

TECHNICAL FIELD

[0001] The present invention relates to a unit for checking the dosingof pharmaceutical material in a production machine.

[0002] In particular, the present invention is advantageously applied ina capsule filling machine for the production of hard gelatin capsulesfor pharmaceutical use, of the type with a capsule lid and a capsulebody containing doses of pharmaceutical material in powder orparticulate form, to which the present specification refers but withoutlimiting the scope of the invention.

BACKGROUND ART

[0003] Generally speaking, a capsule filling machine for the productionof pharmaceutical capsules basically comprises a drum which rotatesabout a vertical axis of rotation, and a circular fixed tank which holdsthe pharmaceutical material to be fed into the capsules by dosing.

[0004] The drum handles and positions the capsules to be filled with thepharmaceutical material by separating the capsule lid from the capsulebody then closing them again once filled. The drum, to which the tankcontaining the material to be dosed is connected, also has a pluralityof doser elements designed to pick up relative doses of material fromthe tank and, respectively, to deposit each dose in the capsule bodybefore the capsule body is closed again with the relative capsule lid.

[0005] According to a known dosing method the doser elements, eachconsisting of a hollow punch, forming a hollow cylinder and housing apiston moving with alternate motion, perform the following operatingsteps one after another: a vertical stroke by the hollow cylinder intothe tank, for immersion in the pharmaceutical material until thecylinder touches the bottom of the tank, forming a dose or slug ofmaterial inside the hollow cylinder; a downward movement by the pistonto compress the dose of pharmaceutical material; a subsequent returnupward movement by the hollow cylinder with the compressed dose stillinside it, to pick up the dose from the tank; finally, with a downwardthrust movement by the piston, the compressed dose is released into therelative capsule body, after an axial movement designed to align thecapsule body on the raised hollow cylinder, by rotation of the drum.

[0006] To correctly pick up the dose then discharge it into the capsulebody but, above all, to ensure that each capsule contains a dose ofpharmaceutical material whose weight lies within a predetermined weightrange, the vertical stroke of the piston operating inside the hollowcylinder is suitably regulated, in both directions, according to valuesdefined as constants and synchronised with the movement of the hollowcylinder.

[0007] To check that the weight of the doses of pharmaceutical materialin the capsules is correct, one known check method involves the use ofprecision scales on which capsules taken as samples from a capsulefilling machine outfeed portion are placed.

[0008] Since such scales have high settling times during weighing steps,this method cannot be used to check all of the capsules produced by thecapsule filling machine, as this would greatly slow down the productionflow.

[0009] To solve the above-mentioned problem, that is to say, to checkall of the capsules produced without slowing down the production flow,at present modern capsule filling machines are fitted with check devicesdesigned to detect the downward force of the pistons during the dosingstep and to control the piston stroke with feedback if said force givesdoses of pharmaceutical material with unacceptable weight values.

[0010] In the capsule filling machine described, for example in U.S.Pat. No. 6,327,835, each dosing piston of a drum rotating withalternating motion is fitted with a force sensor, connected byconnecting cable transmission systems to a control unit designed toreceive, during each pause in the drum alternating motion, a signalrelative to a piston compression force value, to compare said value witha predetermined reference value and to send a feedback signal to adjustthe piston drive unit during the pharmaceutical material dosing steps.

[0011] The control device described in said U.S. patent is validly usedonly on capsule filling machines with alternating motion but, due to theconnecting cable transmission systems, can obviously not be used on acapsule filling machine whose drum rotates continuously at a speed ofrotation which can currently be very high.

DISCLOSURE OF THE INVENTION

[0012] The aim of the present invention is, therefore, to overcome theabove-mentioned disadvantages and the problems of the prior art.

[0013] In particular, the aim of the present invention is to provide acontrol unit which allows an efficient weight check of all of thecapsule produced by a capsule filling machine, whether it operates withcontinuous or alternating motion.

[0014] Accordingly, the present invention provides a unit for checkingthe dosing of pharmaceutical material in a capsule filling machine forthe production of capsules of the type with a capsule lid and a capsulebody, the machine comprising a fixed structure fitted with a rotary drumfor supporting a plurality of capsules on its edge, opening each capsuleby separating the capsule lid from the capsule body, filling the capsulebody with a dose of pharmaceutical material, then closing the capsulebody again with the relative capsule lid. The rotary drum has a tankcontaining the pharmaceutical material and supports a plurality of doserelements, each comprising at least one piston sliding inside a hollowcylinder to pick up and compress a dose of material from the tank anddischarge it into a capsule body of a capsule. The unit is characterisedin that it comprises sensor means attached to each piston to detect apiston thrust value on the dose; transmitter means connected to thesensor means for transmitting the value to a receiver element by thetelemetric transmission of a relative signal, said receiver elementbeing fixed on the machine in at least one area of the fixed structure.Power supply means are also provided for cyclically activating thesensor means and the transmitter means during drum rotation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The technical features of the present invention, in accordancewith the above-mentioned aims, are set out in the claims herein and theadvantages more clearly illustrated in the detailed description whichfollows, with reference to the accompanying drawings, which illustrate apreferred embodiment of the invention without limiting the scope of theinventive concept, and in which:

[0016]FIG. 1 is a schematic top plan view with some parts cut away forgreater clarity, of a capsule filling machine fitted with the unit forchecking the dosing of material according to the present invention;

[0017]FIG. 2 is a side view, partially in cross-section with some partscut away, of a portion of the capsule filling machine illustrated inFIG. 1 in an operating position;

[0018]FIG. 3 is a side view, with some parts cut away and others incross-section, of the capsule filling machine illustrated in FIG. 1 inanother operating position;

[0019]FIG. 4 is a flow diagram illustrating the operation of the unitfor checking the dosing of material according to the present invention;and

[0020]FIG. 5 is a flow diagram illustrating the operation of a part ofthe unit illustrated in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0021] With reference to FIGS. 1, 2 and 3, the numeral 1 denotes acapsule filling machine for the production of capsules CF of the typewith a capsule lid C and a capsule body F containing doses ofpharmaceutical material M in powder or particulate form.

[0022] The machine 1 basically comprises a drum 2 continuously rotatingabout a vertical axis Z and in a clockwise direction B in FIG. 1, itsedge designed to support the capsules CF in a known way and to handleand position the capsules CF at an angle so that they can be filled withdoses of the pharmaceutical material M by separating the capsule lid Cfrom the capsule body F then closing them after filling, with a knownmethod illustrated in FIGS. 2 and 3. The drum 2 is connected to acircular tank 5 containing the pharmaceutical material M supplied to thetank 5 by a material M feed station 100 (FIG. 1).

[0023] The drum 2 has a plurality of known doser elements 3, eachforming a dosing station and designed to pick up doses DS of material Mfrom the tank 5 then deposit each dose DS in the capsule body F of thecapsule CF before the capsule body F is closed again with the relativecapsule lid C.

[0024] As illustrated in FIGS. 2 and 3, each doser element 3 comprises apiston 8 which moves inside a hollow cylinder 4. It should be noticedthat each doser 3 preferably comprises a pair of pistons 8 which moveinside respective hollow cylinders 4, but for the sake of simplicity inthis description and below reference is only made to a single piston 8and a relative cylinder 4 without in any way limiting the scope ofapplication of the invention.

[0025] The cylinder 4 moves vertically in both directions, driven byknown drive means, not illustrated, between a lowered position (FIG. 2)in which the hollow cylinder 4 is immersed in the tank 5, and a raisedposition in which the cylinder 4 is outside the tank 5 (FIG. 3).

[0026] The piston 8 is designed to slide vertically inside the cylinder4, again in both directions, driven by known drive means, notillustrated, in such a way that, in practice, each doser element 3performs the following operating steps one after another: a verticalstroke into the tank 5 by the hollow cylinder 4 so that it is immersedin the pharmaceutical material M until the cylinder touches the bottomof the tank 5, forming a dose DS or slug of material M inside the hollow4 (FIG. 2); a piston 8 downward movement to compress the dose DS ofpharmaceutical material M (FIG. 2); a subsequent hollow cylinder 4return upward movement with the compressed dose DS of material M stillinside the cylinder 4, to pick up the dose from the tank 5; finally,with a piston 8 downward thrust, release of the compressed dose DS intothe relative capsule body F (FIG. 3) carried by slide means 7 on thedrum 2. In practice, the dose DS of material M to be picked up isdefined by the diameter of the cylinder 4, by the piston 8 initialposition and downward stroke.

[0027] As illustrated in FIGS. 1, 2, 4 and 5, the machine 1 comprises aunit 6 for checking the dosing of the material M, which in turncomprises, for each doser element 3, sensor means 9 connected to thepiston 8 to detect and save values V relative to the compression forceexerted by the piston 8 on the dose DS inside the hollow cylinder 4, andtransmitter means 10 connected to the sensor means 9 to transmit thecompression force values V to receiver means 11 by sending relativetransmission signals S.

[0028] The unit 6 also comprises means 12 which supply power to andcyclically activate the sensor means 9 and transmitter means 10 of eachdoser element 3.

[0029] As illustrated in FIGS. 1 and 5, the power supply and cyclicalactivation means 12 comprise means 13 for activating the transmittermeans 10, one for each doser element 3, positioned on the drum 2, andmeans 14 for supplying power to the activation means 13, positioned on afixed portion 15 of the machine 1.

[0030] More specifically, as is better illustrated in FIG. 4, the powersupply and cyclical activation means 12 comprise two stator elements 14(for example, permanent magnets), positioned at relative predeterminedfixed zones P and P1 of the machine 1, and a rotor element 13 (forexample, a coil) connected to each of the doser elements 3. In anembodiment not illustrated, the zones P and P1 coincide, so that thereis only one stator element 14.

[0031] Each rotor element 13 connected to one of the two stator elements14 together define a transformer assembly for the transfer ofelectricity from the stator element 14 to a single rotor element 13 whenthey are positioned close to one another during drum 2 rotation in thedirection B.

[0032] This transfer of electricity is designed to activate the sensormeans 9 and the transmitter means 10, to allow, at the zones P and P1,detection of a value V relative to the piston 8 compression force on thedose DS, subsequently sending the value to the means 10, and, at zone P1only, a subsequent telemetric transmission by radio frequency of asignal S from the transmitter means 10 to the receiver means 11.

[0033] Again as illustrated in the diagram in FIG. 4, further powersupply and cyclical activation means 14 a comprise a third statorelement 14 b positioned in a third fixed, predetermined zone P2 of themachine 1 to allow activation of a single rotor element 13 positioned oneach of the doser elements 3. The zone P2 corresponds to the part of themachine 1 in which each dose DS is discharged into a capsule body F of acapsule CF.

[0034] The third stator element 14 b in the zone P2 is downstream of theother two stator elements 14, relative to the direction B of rotation ofthe drum 2, which are in the zones P and P1 of the machine 1 fixedstructure 15.

[0035] Moreover, the power supply means 14 a power the transmitter means10 in such a way as to allow the telemetric transmission using radiofrequency and by means of a signal S1 to other means 41 of a value V1relative to the discharging force required to discharge the dose DS intothe capsule body F.

[0036] Looking more closely at the construction details in FIGS. 2 and5, each sensor means 9 comprises a pressure transducer or strain gauge17, preferably a load cell 17 positioned on the upper end of thecylinder 4 and connected in a known way to the piston 8. The transmittermeans 10 comprise a transmission unit 10, for example, a transponder,for the signals S and S1 connected directly to the load cell 17 andwhich can be supplied by the rotor element 13 when the latter isactivated by the stator element 14 or 14 b.

[0037] The receiver means 11 and 41, mounted on the machine 1 fixedstructure 15, are also connected, for example by a serial cable, to aprocessing and control device 16 of the type with a microprocessor.

[0038] In the preferred embodiment of the invention disclosed, thesignals S and S1 transmitted by the transmitter means 10 to the receivermeans 11 are electrical signals which are modulated, for example infrequency or amplitude.

[0039] In particular, such modulated signals S and S1 are preferably,although in a non-restricting way, of the digital type.

[0040] For example, the signals S and S1 may be binary and of the knowntype OOK, that is, On-Off Keying, preferably at a frequency of 433 MHz.

[0041] The signals S and S1 received by the receivers 11 and 41 are thensent in turn to the microprocessor processing device 16, so that thedevice 16 can process the values V and V1 of the compression force onthe dose DS and, respectively, of the force for discharging the dose DSinto the capsule body F, comparing them with reference values VF and VF1saved in a device 16 memory area.

[0042] Therefore, in practice, if the value V relative to the piston 8compression force on the dose DS detected by the load cell 17 andtransmitted to the receiver 11 and then to the device 16 is not in linewith the reference value VF with which it is compared, the device 16activates means 30, preferably of the pneumatic type with a pressurisedair jet, to expel the capsule CF whose dose DS was compressed with acompression force with value V, the means 30 being positioned at amachine 1 outfeed portion 31.

[0043] If, instead the value V1 relative to the discharging forceexceeds the limit value VF1, the capsule filling machine 1 automaticallystops, to avoid the consequent possibility of damage to the cylinder 4and/or the piston 8.

[0044] Again as illustrated in FIG. 4, the unit 6 also comprises adevice 32 for manual entry of a weight value to be the predeterminedvalue for the doses DS of material M which will fill the capsules CF inthe machine 1. Similarly, a value VF1 corresponding to a limit force fordischarging the dose DS into the capsule body F by the piston 8 can alsobe set manually.

[0045] The device 32 is connected, for example by a serial cable, to themicroprocessor device 16, whose memory contains a special algorithm forconversion of the above-mentioned weight value (for example expressed inmilligrams) into a corresponding thrust force value (for exampleexpressed in Newtons) which must be generated by the pistons 8 and whichwill define the reference values VF and VF1.

[0046] The microprocessor device 16 is also connected to a device 33 forweighing the finished capsules CF with a predetermined statisticalcyclicity.

[0047] This device 33 is designed to send the microprocessor device 16 asignal SP equivalent to the actual weight of the capsule CF to allowverification through feedback of correct operation of the comparisonsmade by the microprocessor device 16, and therefore, correct operationof the control unit 6.

[0048] The microprocessor device 16 also controls a device 34 forgenerating a feedback signal to adjust the stroke of each piston 8 inthe relative hollow cylinder 4, preferably based on a mean evaluation ina given production time interval.

[0049] In practice the unit 6 operates as follows.

[0050] With the machine 1 stopped, the operator uses the device 32 toset the weight value which will be the predetermined value for the dosesDS of material M that will fill the capsules CF. In this way, the device16 can process the piston 8 compression force reference value VF. Thedischarging force limit value VF1 is set in the same way.

[0051] At this point the machine 1 may begin the production cycle andwhen each of the doser elements 3, during continuous rotation of thedrum 2, is cyclically adjacent to the first stator element 14 fixed inthe first predetermined zone P the load cell 17 is energised by therotor 13, in turn activated by the stator 14, and can record the piston8 compression force on the dose DS inside the cylinder 4.

[0052] Next, the doser element 3 moves to the second fixed zone P1 inwhich the second stator element 14 is present.

[0053] The load cell 17 energised by the rotor 13 sends the value Vrelative to the piston 8 compression force previously recorded to thetransmitter 10, which is also energised by the rotor 13 and transmitsthe signal S to the fixed receiver 11 which, in turn, sends the samesignal S to the microprocessor device 16.

[0054] In this way, the device 16 can compare the value V sent by meansof the signal S with the reference value VF and make the followingchoices: if the value V lies within the predetermined range set aroundVF the finished capsule CF is then fed out of the machine 1 as normal atthe portion 31. If the value V is unacceptable relative to the value VF,that is to say, if the value V is not within the predetermined rangearound VF, the device 16 activates the rejection means 30 to expel andreject the capsule CF from the capsule filling machine 1 into a rejectsbin (not illustrated).

[0055] Continuous movement of the drum 2 in the direction B then bringsthe doser element 3 to the third stator element 14 b positioned in thepredetermined machine 1 zone P2, again activating the load cell 17 torecord the value V1 relative to the discharging force exerted by thepiston 8 on the dose DS during dose DS discharging into the capsule bodyF.

[0056] This value V1 is immediately sent by means of the signal S1, fromthe transmitter 10 to the fixed receiver 41 and then to themicroprocessor device 16.

[0057] The microprocessor device compares it with the reference valueVF1 previously entered using the device 32, to check that thedischarging force is correct: if the value V1 is lower than the limitvalue VF1 the production cycle continues. Otherwise, the machine 1 stopsto prevent breakage or damage to the cylinder 4 and/or the piston 8.

[0058] The microprocessor device 16 is also designed to activate thedevice 34 which adjusts the stroke of the piston 8 whose compressionvalue V was detected outside the predetermined range, to adjust thestroke of the piston 8.

[0059] To guarantee the efficiency of the checking system implemented bythe microprocessor device 16, capsules CF considered to be of thecorrect weight are weighed on the weighing device 33 with apredetermined statistical cyclicity.

[0060] This device 33 sends a signal SP to the microprocessor device 16equivalent to the actual weight of the capsule CF obtained, so as toverify the correct operation of the comparisons made by the device 16.

[0061] In the event of discrepancies between the actual weight and thedata saved by the device 16, the operator may act directly or there maybe an automatic system in the device 16 for correcting the comparisondata.

[0062] A control unit 6 structured in this way, therefore, achieves thepreset aims thanks to an extremely rapid system for checking the dosingof all capsules produced in the continuous-motion capsule fillingmachine 1, practically in real time, thanks to the system for radiofrequency transmission of modulated electrical signals, without slowingdown capsule filling machine 1 production at all.

[0063] The high speed, precision and flexibility of the system allow itsuse on all types of continuous-motion capsule filling machines and evenon those with alternating motion, with both high and low productionspeeds.

[0064] The invention described can be subject to modifications andvariations without thereby departing from the scope of the inventiveconcept. Moreover, all the details of the invention may be substitutedby technically equivalent elements.

1. A unit (6) for checking the dosing of pharmaceutical material (M) ina capsule filling machine (1) for the production of capsules (CF) of thetype with a capsule lid (C) and a capsule body (F), the machine (1)comprising a fixed structure (15) fitted with a rotary drum (2) forsupporting a plurality of capsules (CF) on its edge, opening eachcapsule (CF) by separating the capsule lid (C) from the capsule body(F), filling the capsule body (F) with a dose (DS) of material (M), thenclosing the capsule body (F) again with the relative capsule lid (C);the rotary drum (2) having a tank (5) containing the pharmaceuticalmaterial (M) and supporting a plurality of doser elements (3), eachcomprising at least one piston (8) sliding inside a hollow cylinder (4)to pick up and compress a dose (DS) of material (M) from the tank (5)and discharge it into a capsule body (F) of a capsule (CF); the unit (6)being characterised in that it comprises sensor means (9) attached toeach piston (8) for detecting a piston (8) thrust value (V; V1) on thedose (DS); transmitter means (10) connected to the sensor means (9) fortransmitting the value (V; V1) to a receiver element (11; 41) by thetelemetric transmission of a relative signal (S; S1), said receiverelement (11; 41) being fixed on the machine (1) in at least one zone(P1; P2) of the fixed structure (15); there also being power supplymeans (12, 14 a) for cyclically activating the sensor means (9) and thetransmitter means (10) during drum (2) rotation.
 2. The unit accordingto claim 1, characterised in that the signal (S; S1) is transmitted inradio frequency.
 3. The unit according to claim 1 or 2, characterised inthat the signal (S; S1) is a modulated signal.
 4. The unit according toany of the claims from 1 to 3, characterised in that the sensor means(9) comprise a load cell (17) connected to each of the pistons (8) fordetecting a value (V) relative to the piston (8) compression force onthe dose (DS) and for sending a signal (S) to the receiver element (11)through the transmitter means (10).
 5. The unit according to any of theclaims from 1 to 4, characterised in that the sensor means (9) comprisea load cell (17) connected to each of the pistons (8) for detecting avalue (V1) relative to the piston (8) discharging force on the dose (DS)while discharging the dose (DS) into the capsule body (F) and forsending a signal (S1) to the receiver element (41) through thetransmitter means (10).
 6. The unit according to any of the claims from1 to 5, characterised in that the power supply means (12; 14 a) comprisea stator element (14; 14 b) in a fixed position in at least one zone (P,P1; P2) of the fixed structure (15) and a rotor element (13) attached toeach of the rotary drum (2) doser elements (3).
 7. The unit according toany of the claims from 1 to 6, characterised in that it also comprises aprocessing and control device (16) connected to the receiver element(11; 41) and to capsule (CF) rejection means (30); the processing andcontrol device (16) being designed to compare the value (V; V1) receivedfrom the receiver element (11; 41) by means of the signal (S; S1) with arelative reference value (VF; VF1) and to activate the rejection means(30) if the value (V; V1) is unacceptable relative to the referencevalue (VF; VF1).
 8. The unit according to claim 7, characterised in thatit comprises a device (32) for manual data entry, connected to theprocessing and control device (16), for generating the reference value(V1; VF1) in the processing and control device (16).
 9. The unitaccording to claim 7 or 8, characterised in that it also comprises adevice (34) for generating a feedback signal to adjust the stroke ofeach piston (8) in the relative hollow cylinder (4), this device beingcontrolled by the processing and control device (16).
 10. The unitaccording to any of the claims from 7 to 9, characterised in that italso comprises a device (33) for weighing the capsules (CF), this devicebeing controlled by the processing and control device (16).